JP2009082850A - New gas separation membrane, its manufacturing method, and gas treating method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas separation membrane with high selectivity of carbon dioxide and nitrogen, and its manufacturing method. <P>SOLUTION: The gas separation membrane is formed by carrying alkali metals, alkaline earth metals and/or amine compounds on a carbon membrane using a cardo-type polyimide as a raw material, and its manufacturing method is provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a novel gas separation membrane, a method for producing the same, and a gas treatment method using the same, and more particularly, alkali metals and alkaline earths useful as gas separation membranes for separating carbon dioxide and other gases, particularly nitrogen. The present invention relates to a metal and / or amine compound-supporting carbon film, a production method thereof, and a gas treatment method using the same.

As a global warming countermeasure technique, a technique that separates and collects carbon dioxide (CO ₂ ) emitted by the combustion of fossil fuel and stores it in the ground is drawing attention. In addition, great expectations are placed on membrane separation technology as a measure for significantly reducing CO ₂ separation costs. Further, in the CO ₂ separation and recovery type coal gasification combined power generation (IGCC) process, a highly efficient separation membrane of CO ₂ and H ₂ is required. Development of membrane separating this manner the CO ₂ and the like highly selectively N ₂ or H ₂ is urgent.

A carbon membrane, which is one of the inorganic membranes, has been reported to exhibit CO ₂ / N ₂ gas separation performance because of its inherent gas permeability. However, this separation performance is not always satisfactory.

  In general, a carbon membrane has gas separation ability, but it is known that gas separation performance is reduced in an atmosphere containing moisture (Non-patent Document 1).

Therefore, it is desired to develop a separation membrane exhibiting excellent CO ₂ / N ₂ gas separation performance even in an atmosphere containing moisture.

  On the other hand, a separation membrane in which diaminopropionic acid and cesium are supported on a polyvinyl alcohol-acrylic acid copolymer (PVA-PAA) membrane is also known (Non-patent Document 2). However, such a separation membrane has a drawback that it is unstable with respect to changes in humidity.

Japanese Patent Laid-Open No. 10-99664 Ind. Eng. Chem. Res. 1995, 34, pp. 158-163 Membrane, Vol. 30, no. 1 (2005), pp. 46-51

An object of the present invention is to provide a novel separation membrane exhibiting excellent CO ₂ / N ₂ gas separation performance even in an atmosphere containing moisture.

In order to solve the above-mentioned problems, the present inventors have conducted extensive research and, as a result, by carrying an alkali metal, an alkaline earth metal and / or an amine compound on a carbon film made of cardo type polyimide as a raw material, The inventors have found that a separation membrane exhibiting excellent CO ₂ / N ₂ gas separation performance can be obtained even in an atmosphere including the above, and have further researched to complete the present invention.
That is, the present invention

の関係にある前記［１］〜［８］のいずれかに記載のガス分離膜、
［１０］ 膜温度４０℃、バブラー温度４０℃、供給ガス組成ＣＯ_２／Ｎ_２（５／９５ｖｏｌ％）で差圧法（供給側大気圧、透過側減圧）にて測定して得られるＣＯ_２パーミアンス（Ｑ_ＣＯ２）が式２

の関係にある前記［１］〜［９］のいずれかに記載のガス分離膜、
［１１］ カルド型ポリイミド溶液のディップコーティングにより多孔性支持膜の外表面上にコーティング層を形成させたのち、嫌気性雰囲気下に加熱してコーティング層を炭化してカーボン膜を形成させ、ついでアルカリ金属の塩、アルカリ土類金属の塩および／またはアミン化合物を含有した溶液に浸漬したのち乾燥して前記カーボン膜に前記アルカリ金属、アルカリ土類金属および／またはアミン化合物を担持させることを特徴とするガス分離膜の製造方法、
［１２］ カルド型ポリイミドとアルカリ金属の塩および／またはアルカリ土類金属の塩を含有する溶液のディップコーティングにより多孔性支持膜の外表面上にコーティング層を形成させたのち、嫌気性雰囲気下に加熱してコーティング層を炭化してカーボン膜を形成させると同時に前記カーボン膜に前記アルカリ金属および／またはアルカリ土類金属を担持させることを特徴とするガス分離膜の製造方法、および
［１３］ 前記［１］〜［１０］のいずれかに記載のガス分離膜を用いて、ＣＯ_２を含む混合ガスからＣＯ_２を分離する方法、
に関する。 [1] A gas separation membrane comprising an alkali metal, an alkaline earth metal and / or an amine compound supported on a carbon membrane made of cardotype polyimide as a raw material,
[2] The gas separation membrane according to [1], wherein an alkali metal, an alkaline earth metal and / or an amine compound is supported on the surface and / or the inside of the carbon membrane.
[3] The gas separation membrane according to [1] or [2], wherein the carbon membrane is laminated on one surface of a porous support membrane,
[4] The gas separation membrane according to [3], wherein the porous support membrane is tubular,
[5] The gas separation membrane according to [3] or [4], wherein the porous support membrane is an alumina porous membrane,
[6] The gas separation membrane according to any one of [1] to [5], wherein the carbon membrane is an asymmetric membrane,
[7] The gas separation membrane according to any one of [1] to [6], wherein the alkali metal is lithium, sodium, potassium, rubidium or cesium, and the alkaline earth metal is calcium, strontium or barium.
[8] The gas separation membrane according to any one of [1] to [7], wherein the amine compound is an aliphatic amine compound, an aromatic amine compound, or an amino acid.
[9] Separation coefficient α obtained by measurement by a differential pressure method (supply-side atmospheric pressure, permeation-side reduced pressure) with a membrane temperature of 40 ° C., a bubbler temperature of 40 ° C., and a supply gas composition CO ₂ / N ₂ (5/95 vol%). (P _CO2 / P _N2 ) is the formula 1

The gas separation membrane according to any one of [1] to [8],
[10] CO ₂ permeance obtained by measurement by a differential pressure method (supply-side atmospheric pressure, permeation-side reduced pressure) with a membrane temperature of 40 ° C., a bubbler temperature of 40 ° C., and a supply gas composition CO ₂ / N ₂ (5/95 vol%). _{(Q CO2)} has the formula 2

The gas separation membrane according to any one of [1] to [9],
[11] After forming a coating layer on the outer surface of the porous support membrane by dip coating with a cardo type polyimide solution, the coating layer is carbonized by heating in an anaerobic atmosphere, and then an alkali is formed. It is soaked in a solution containing a metal salt, an alkaline earth metal salt and / or an amine compound, and then dried, and the alkali metal, alkaline earth metal and / or amine compound is supported on the carbon film. A method for producing a gas separation membrane,
[12] After forming a coating layer on the outer surface of the porous support membrane by dip coating of a solution containing a cardotype polyimide and an alkali metal salt and / or an alkaline earth metal salt, the solution is placed in an anaerobic atmosphere. Heating the carbonized coating layer to form a carbon film, and simultaneously supporting the alkali metal and / or alkaline earth metal on the carbon film, and [13] A method for separating CO ₂ from a mixed gas containing CO ₂ using the gas separation membrane according to any one of [1] to [10];
About.

Gas separation membranes of the present invention exhibits remarkably excellent gas separation performance even under water-containing atmosphere, other efficient CO ₂ by contacting the mixed gas with other gas and CO ₂ in the gas separation membrane Can be separated from the other gas.

  The gas separation membrane of the present invention is characterized in that an alkali metal, an alkaline earth metal and / or an amine compound are supported on a carbon membrane made from cardo type polyimide.

（ただし、Ｙは４価の有機残基を示し、Ｘは２価の有機残基であって少なくともその一部は下記構造式［Ａ］

（ただし、Ｒ_１〜Ｒ_１２は同一または異なって、水素原子、Ｃ１−４のアルキル記、Ｃ１−４のアルコキシ基、カルボキシル基、Ｃ２−Ｃ５のアルコキシカルボニル基、またはハロゲン原子を示す）で示される２価の有機残基を示す）
で示されるポリイミド構造単位を有するカルド型ポリイミドが挙げられる。 Cardo-type polyimide The carbon film according to the present invention is produced using cardo-type polyimide as a raw material. Here, the cardo type polyimide is a general term for polyimides having a fluorene skeleton, for example, the general formula [I] described in JP-A-10-99664.

(Wherein Y represents a tetravalent organic residue, X represents a divalent organic residue, and at least a part thereof is represented by the following structural formula [A].

(Wherein R _{1 to} R ₁₂ are the same or different and each represents a hydrogen atom, a C1-4 alkyl, a C1-4 alkoxy group, a carboxyl group, a C2-C5 alkoxycarbonyl group, or a halogen atom). Divalent organic residue)
And a cardo type polyimide having a polyimide structural unit represented by

  Such cardo-type polyimide can be obtained by reacting diamines with tetracarboxylic dianhydride, for example, according to the method described in JP-A-5-192552.

  Examples of the tetracarboxylic dianhydride used as a raw material for the Y moiety in the compound represented by the general formula (1) include, for example, pyromellitic anhydride and 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride. Bis (3,4-dicarboxyphenyl) sulfone dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4′4-diphenyl ether tetracarboxylic dianhydride, and the like, and mixtures thereof.

Among these, preferable tetracarboxylic dianhydrides include, for example, compounds represented by the following structural formula.

（ただし、Ｒ_１〜Ｒ_１２は構造式［Ａ］の場合と同じである。）
で示されるジアミン類があげられる。このジアミン類は単独で使用してもよく、あるいはこのフルオレン骨格を有するジアミン類とその他のジアミン類を併用して使用してもよい。 In the general formula (I), as a raw material for the X portion, the following general formula (A-1)

(However, R _{1 to} R ₁₂ are the same as in the structural formula [A].)
And diamines represented by the formula: These diamines may be used alone or in combination with diamines having this fluorene skeleton and other diamines.

  Examples of the diamine having a fluorene skeleton include bisaniline fluorenes, specifically 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (3-methyl-4-amino). Phenyl) fluorene, 9,9-bis (3,5-dimethyl-4-aminophenyl) fluorene, 9,9-bis (3-ethyl-4-aminophenyl) fluorene, 9,9-bis (3,5- Diethyl-4-aminophenyl) fluorene, 9,9-bis (3-bromo-4-aminophenyl) fluorene, 9,9-bis (3,5-dibromo-4-aminophenyl) fluorene, 9,9-bis Examples include (4-aminophenyl) fluorene-4-carboxylic acid, 9,9-bis (4-aminophenyl) fluorene-4-carboxylate methyl, and mixtures thereof. That.

  Examples of other diamines include aromatic diamines such as 2,7-diaminofluorene, naphthalenediamine, 2,8-diaminodibenzofuran, 4,4′-diaminobiphenyl, 4,4′-diaminodiphenyl ether, Examples include aliphatic diamines such as hexamethylene diamine and isopropyl diamine, diamino alkylene glycols such as diaminoethylene glycol and diaminopropylene glycol, and diaminopolyalkylene glycols such as diaminopolyethylene glycol and diaminopolypropylene glycol.

  In the general formula (I), the component weight ratio between the diamine having a fluorene skeleton and the other diamines is preferably 10% or more with respect to the total amount of the former. If it is less than 10%, excellent solvent solubility and thermal stability cannot be obtained for the precursor cardo type polymer.

When a specific example of the cardo type polyimide obtained above is exemplified, the following structural formula is exemplified.

上記した式（１）〜（６）において、ｘおよびｙはモル分率を表し、ｍおよびｎはユニットの繰り返し数を表す。 Further, specific examples of cardotype polyimides obtained by using a diamine having a fluorene skeleton and other diamines (for example, hexamethylenediamine, poly (oxyethylene) dipropylamine 10,000, etc.), The following structural formulas are listed.

In the above formulas (1) to (6), x and y represent mole fractions, and m and n represent the number of repeating units.

Formation of Carbon Film A coating layer is formed on the outer surface of the porous support film by dip coating of a solution containing the above cardo type polyimide. Here, the cardo type polyimide is a material before carbonizing into carbon, and is also referred to as a precursor in this specification. If necessary, polyethylene glycol (PEG), polypropylene glycol (PPG) or the like may be added to the solution containing this precursor for the purpose of improving the properties of the carbon film. Further, when adopting the supporting method 1 described later, an alkali metal salt or an alkaline earth metal salt is added to the solution. The solvent of the solution is not particularly limited, and examples thereof include 1-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and the like.
The coating layer can take the structure of a homogeneous membrane, asymmetric membrane, or composite membrane, and there are flat membranes, hollow fiber membranes, tubular membranes, etc., and the appropriate membrane structure and membrane shape can be used depending on the purpose. The coating layer which has can be formed.

  By heating the coating layer formed on the outer surface of the porous support film in an anaerobic atmosphere, the cardo type polyimide in the precursor is carbonized to form a carbon film. Here, the anaerobic atmosphere can be formed by filling or circulating an inert gas containing no oxygen, such as nitrogen, helium, and argon, or by reducing the pressure inside the heating container. . The temperature at which the carbon film precursor is heated and carbonized (carbonization temperature) is usually 300 to 2000 ° C., preferably 500 to 1500 ° C., more preferably, although it depends on the type of the precursor containing cardo type polyimide. It is 500-900 degreeC. If the temperature is lower than 300 ° C, carbonization does not proceed sufficiently, making it difficult to obtain excellent separation performance. On the other hand, if the temperature is higher than 2000 ° C, decomposition of the precursor containing cardo-type polyimide is increased, and the carbon membrane is reduced. The rate decreases and a good carbon film cannot be obtained. The carbonization time is usually from 10 minutes to 24 hours, although it depends on the carbonization temperature and the type and amount of the precursor containing cardo type polyimide. Thus, a carbon film is formed on the outer surface of the porous support film.

Supporting alkali metal, alkaline earth metal and / or amine compound Next, the carbon film formed above is supported with alkali metal, alkaline earth metal and / or amine compound. The supporting method is not particularly limited as long as it is a method for uniformly and stably holding the alkali metal, alkaline earth metal and / or amine compound on the surface and / or inside of the carbon film, but the following method is preferably used. Can be adopted.

  Alkali metals or alkaline earth metals are used in the form of their carbonates or bicarbonates. Specifically, alkali metal carbonates such as lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, and cesium carbonate, carbonates are used. Examples include alkaline earth metal carbonates such as calcium, strontium carbonate, and barium carbonate.

Examples of amine compounds include aliphatic amine compounds such as methanolamine, monoethanolamine, diethanolamine, triethanolamine, and 3-dimethylaminopropylamine, and aromatic amine compounds such as aniline, methylaniline, dimethylaniline, and benzylamine. , Amino acids such as 2,3-diaminopropionic acid and glycine.
The alkali metal, alkaline earth metal and amine compound as described above may be used alone or in combination of two or more.

  As a method of supporting an alkali metal, alkaline earth metal and / or amine compound on a carbon film, a method of carbonizing an alkali metal and / or alkaline earth metal mixed in a precursor (supporting method 1) and a carbon film There is a method (supporting method 2) in which an alkali metal, an alkaline earth metal and / or an amine compound is supported after the production.

Loading method 1:
The first supporting method is a method in which an alkali metal and / or an alkaline earth metal is added to the precursor and then carbonized. The alkali metal and / or alkaline earth metal is added to the precursor solution in the form of its carbonate or bicarbonate.

  As a method of adding an alkali metal and / or alkaline earth metal to the precursor, there is a method of dissolving and mixing a cardo type polyimide or the like and an alkali metal salt and / or an alkaline earth metal salt in an appropriate solvent. The solvent is not particularly limited as long as it dissolves the compound constituting the precursor. For example, 1-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) ) And the like.

  In addition, water, methanol, ethanol, 1-propanol, 2-propanol and the like can be added as the third component for the purpose of improving the solubility of the compound constituting the precursor.

  When precipitation occurs in the process of adding alkali metal and / or alkaline earth metal to the precursor using the above method, the supernatant liquid can be used as the coating liquid.

Loading method 2:
The second supporting method is a method of supporting an alkali metal, alkaline earth metal and / or amine compound after producing a carbon film. One or two of alkali metal, alkaline earth metal alkali metal and amine compound are supported. More than one can be carried.

  In order to support an alkali metal, alkaline earth metal and / or amine compound on a carbon film by this method, the carbon film is immersed in a treatment solution containing an alkali metal salt, an alkaline earth metal salt and / or an amine compound. Can be performed. The concentration of the alkali metal, alkaline earth metal and / or amine compound in the treatment liquid may be not more than the saturation concentration. The solvent of the treatment liquid is not particularly limited as long as it can dissolve an alkali metal salt, an alkaline earth metal salt and / or an amine compound, and examples thereof include water, an aqueous methanol solution, and an aqueous ethanol solution. . Although the processing temperature at the time of immersion is not specifically limited, 10-60 degreeC is preferable. The immersion time is preferably 0.1 to 48 hours.

の関係にあり、好ましくはこの関係に加えて、さらに同条件で測定して得られるＣＯ_２パーミアンス（Ｑ_ＣＯ２）が式（２）：

の関係にあるのが好ましい。 The gas separation membrane thus obtained is measured by a differential pressure method (supply-side atmospheric pressure, permeation-side reduced pressure) with a membrane temperature of 40 ° C., a bubbler temperature of 40 ° C., and a supply gas composition CO ₂ / N ₂ (5/95 vol%). The resulting separation factor α (P _CO2 / P _N2 ) is _expressed by the formula (1):

Preferably, in addition to this relationship, CO ₂ permeance (Q _CO2 ) obtained by further measurement under the same conditions is expressed by the formula (2):

It is preferable that

CO ₂ Separation Method Another aspect of the present invention is a method for separating CO ₂ from a mixed gas containing carbon dioxide (CO ₂ ) using the gas separation membrane obtained above. That is, the gas separation method of the present invention includes a step of bringing the mixed gas containing CO ₂ into contact with the gas separation membrane obtained above to selectively permeate CO ₂ in the mixed gas. .

  In the gas separation method, it is necessary to provide a pressure difference between the gas supply side and the gas permeation side of the separation membrane. This pressure difference is provided by depressurizing the gas permeation side or pressurizing the supply side, or by using both in combination. The operating temperature of this separation method can be preferably used as long as the separation membrane can withstand the temperature and the water vapor in the supply gas and permeate gas does not freeze. It is more preferable to carry out the reaction under a temperature condition of 25 to 180 ° C, more preferably 25 to 150 ° C.

The mixed gas applicable to the separation method of the present invention is not particularly limited as long as it is a mixed gas containing CO ₂ , but in order to improve the separation performance between CO ₂ and other gases, the relative humidity of the mixed gas is set to 30. % Or more, preferably 60 to 100%, more preferably 80 to 100%.

The gas separation method can be applied to separate CO ₂ from combustion exhaust gas generated in, for example, a thermal power plant or a steel plant.

  Hereinafter, the present invention will be described with reference to synthesis examples, examples and test examples, but the present invention is not limited to these synthesis examples, examples and test examples. In the synthesis examples and examples, “PI-co-PEG10000” is a cardo type polyimide synthesized from bisaminophenylfluorene, poly (oxyethylene) dipropylamine 10,000, and benzophenonetetracarboxylic dianhydride. “PI-BTCOOMe” is an abbreviation for a cardo type polyimide synthesized from bisaniline-fluorene-4-carboxylic acid methyl ester and benzophenone tetracarboxylic dianhydride.

（上記式中、記号は前記と同一意味を有する。） [Synthesis Example 1]
(Synthesis of PI-co-PEG10000)
In a separable flask under a nitrogen stream, 4.8 g of bisaminophenylfluorene (that is, 9,9-bis (4-aminophenyl) fluorene) as a diamine and 10,000 (average) of poly (oxyethylene) dipropylamine 8.5 g of molecular weight 10,000) and 4.7 g of benzophenone tetracarboxylic dianhydride (that is, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride) as an acid anhydride, The polymer was dissolved in -2-pyrrolidone (NMP) and then polymerized while maintaining the solution temperature at 180 ° C. and removing the water produced. The obtained solution was dropped into a large amount of methanol, precipitated, filtered, and dried to obtain a cardo type polyimide resin. The structural formula of the obtained cardo type polyimide resin PI-co-PEG10000 is shown below.

(In the above formula, the symbols have the same meaning as described above.)

（式中、ｎは前記と同一意味を有する） [Synthesis Example 2]
(Synthesis of PI-BTCOOMe)
Bisaniline-fluorene-4-carboxylic acid methyl ester (that is, methyl 9,9-bis (4-aminophenyl) fluorene-4-carboxylate) as a diamine in a separable flask under a nitrogen stream, and an acid anhydride As benzophenone tetracarboxylic dianhydride (ie, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride) is dissolved in the solvent NMP and the solution temperature is kept at 180 ° C. Polymerization was conducted while removing. The obtained solution was dropped into a large amount of methanol, precipitated, filtered, and dried to obtain a cardo type polyimide resin. The structural formula of the obtained cardo type polyimide resin PI-BTCOOMe is shown below.

(Wherein n has the same meaning as above)

[Example 1]
An NMP solution containing 5 weight percent of PI-co-PEG10000 synthesized in Synthesis Example 1 was prepared. While stirring 36 g of this precursor solution (5 wt% PI-co-PEG10000 / NMP) in a beaker, 4 g of 1N K ₂ CO ₃ aqueous solution (Wako Pure Chemical Industries) was dropped using a Pasteur pipette, and the mixture was stirred overnight. Continued. Since precipitation (solid matter) occurred in the precursor solution, the supernatant liquid was poured into a dip coating measuring cylinder, and a tubular alumina porous support membrane (Noritake Company Limited, outer diameter 10 mm, pore diameter 150 nm) (bottom end) Using a teflon seal), dip coating was performed using a dipping apparatus (Filgen Co., Ltd.) (immersion time 1 minute, lifting speed 1 cm / s). The sample after dip coating was dried overnight in an oven at 60 ° C. in air. In this way, an alumina support membrane coated with the precursor is obtained. Thereafter, carbonization was performed under the conditions of nitrogen atmosphere, 200 ° C. for 2 hours, 600 ° C. for 3 hours, temperature increase, and cooling rate of 5 ° C./min. In this manner, a carbon membrane was formed on the surface of the porous alumina support membrane, and at the same time, a gas separation membrane was prepared in which potassium (K) was supported on the carbon membrane.

[Example 2]
A carbon membrane was formed on the surface of the alumina porous support membrane at the same time as in Example 1 except that 1 g of 10 wt% K ₂ CO ₃ aqueous solution was added dropwise instead of 1N K ₂ CO ₃ aqueous solution. A gas separation membrane having potassium (K) supported on a carbon membrane was produced.

[Example 3]
When a carbon membrane was formed on the surface of the alumina porous support membrane by treating in the same manner as in Example 1 except that 0.5 g of 10 wt% K ₂ CO ₃ aqueous solution was dropped instead of 1N K ₂ CO ₃ aqueous solution, At the same time, a gas separation membrane having potassium (K) supported on the carbon membrane was produced.

[Example 4]
An NMP solution containing 5 weight percent of PI-co-PEG10000 synthesized in Synthesis Example 1 was prepared and used as a precursor solution (5 wt% PI-co-PEG10000 / NMP). Using a tubular alumina porous support membrane (Noritake Company Limited, outer diameter 10 mm, pore diameter 150 nm) (bottom diameter sealed with Teflon seal), dip coating was performed using a dipping device (Filgen Co., Ltd.) ( Immersion time 1 minute, lifting speed 1 cm / s). The sample after dip coating was dried overnight in an oven at 60 ° C. in air. In this way, a composite membrane in which the precursor was coated on the surface of the support membrane was obtained. Thereafter, carbonization was performed under the conditions of nitrogen atmosphere, 200 ° C. for 2 hours, 600 ° C. for 3 hours, temperature increase, and cooling rate of 5 ° C./min. One end of the carbon film after carbonization is sealed with an adhesive, and a stainless steel tube having an outer diameter of 10 mm and a length of 50 mm is bonded to the other end. The outside of the membrane was immersed in a 10 wt% K ₂ CO ₃ (Wako Pure Chemicals) aqueous solution at room temperature for 12 hours to carry K ₂ CO ₃ . Thus, a gas separation membrane in which potassium (K) was supported on the carbon membrane was produced.

[Example 5]
An NMP solution containing 7 weight percent of PI-BTCOOMe synthesized in Synthesis Example 2 was prepared. By using this precursor solution (7 wt% PI-BTCOOMe / NMP), except that 4 g of 10 wt% CsCO ₃ aqueous solution was added dropwise instead of 1 N K ₂ CO ₃ aqueous solution, the same treatment as in Example 1 was performed. A gas separation membrane was produced in which a carbon membrane was formed on the surface of the carbon support membrane and at the same time cesium (Cs) was supported on the carbon membrane.

[Example 6]
An NMP solution containing 7 percent by weight of PI-BTCOOMe synthesized in Synthesis Example 2 was prepared and used as a precursor solution (7 wt% PI-BTCOOMe / NMP). Using a tubular alumina porous support membrane (Noritake Company Limited, outer diameter 10 mm, pore diameter 150 nm) (bottom diameter sealed with Teflon seal), dip coating was performed using a dipping device (Filgen Co., Ltd.) ( Immersion time 1 minute, lifting speed 1 cm / s). The sample after dip coating was dried overnight in an oven at 60 ° C. in air. In this way, a composite membrane in which the precursor was coated on the surface of the support membrane was obtained. Thereafter, carbonization was performed under the conditions of nitrogen atmosphere, 200 ° C. for 2 hours, 600 ° C. for 3 hours, temperature increase, and cooling rate of 5 ° C./min. One end of the carbon film after carbonization is sealed with an adhesive, and a stainless steel tube having an outer diameter of 10 mm and a length of 50 mm is bonded to the other end. The adhesive stainless tube was connected to a vacuum pump for 1 hour at room temperature the membranes outside in a state where the film inside the reduced pressure, _Li 2 CO ₃ solution _{(composition: 1.5g-Li 2 CO 3 /} 100g-H 2 O) Then, Li ₂ CO ₃ was supported thereon. Thus, a gas separation membrane in which lithium (Li) was supported on the carbon membrane was produced.

[Example 7]
But using solution _{of Na} 2 CO ₃ instead of li ₂ CO ₃ solution _{(29.4g-Na 2 CO 3 /} 100g-H 2 O) is treated in the same manner as in Example 6, sodium carbon film (Na ) Was prepared.

[Example 8]
Except that in place of li ₂ CO ₃ solution using _K 2 CO ₃ solution _{(112.1g-K 2 CO 3 /} 100g-H 2 O) is treated in the same manner as in Example 6, potassium carbon film (K ) Was prepared.
[Example 9]
But using _Rb 2 CO ₃ solution in place of li ₂ CO ₃ solution _{(225g-Rb 2 CO 3 /} 100g-H 2 O) is treated in the same manner as in Example 6, rubidium (Rb) in the carbon film A supported gas separation membrane was produced.

[Example 10]
But using _Cs 2 CO ₃ solution in place of li ₂ CO ₃ solution _{(260.5g-Cs 2 CO 3 /} 100g-H 2 O) is treated in the same manner as in Example 6, the carbon film cesium (Cs ) Was prepared.

[Example 11]
But using _Cs 2 _CO 3 + 2,3- diaminopropionic acid (DAPA) solution _{(260.5g-Cs 2 CO 3 /} 50g-DAPA / 100g-H 2 O) in place of li ₂ CO ₃ solution, Example In the same manner as in No. 6, a gas separation membrane in which cesium (Cs) and 2,3-diaminopropionic acid (DAPA) were supported on a carbon membrane was produced.

[Comparative Example 1]
40 g of a precursor solution (5 wt% PI-co-PEG10000 / NMP (Aldrich) solution) was prepared. This was poured into a dip-coating graduated cylinder and a tubular alumina support membrane (Noritake Company Limited, outer diameter 10 mm, pore diameter 150 nm) (bottom end sealed with Teflon seal) and dipping device (Filgen Co., Ltd.) ) Was used to perform dip coating (immersion time 1 minute, elevating speed 1 cm / s). The sample after dip coating was dried overnight in an oven at 60 ° C. in air. In this way, a composite membrane in which the precursor was coated on the surface of the support membrane was obtained. Thereafter, carbonization was performed under the conditions of nitrogen atmosphere, 200 ° C. for 2 hours, 600 ° C. for 3 hours, temperature increase, and cooling rate of 5 ° C./min. In this way, a carbon membrane was produced on the surface of the alumina porous support membrane.

[Comparative Example 2]
A carbon membrane was produced on the surface of the porous alumina support membrane in the same manner as in Comparative Example 1 except that a 7 wt% PI-BTCOOMe / NMP (Aldrich) solution was used as the precursor solution.
Table 1 below summarizes the support materials, precursors and treatment methods used in the examples and comparative examples.

[Test Example] CO ₂ and N ₂ Separation Test CO ₂ separation ability was measured using the gas separation membranes obtained in Examples 1 to 11 and Comparative Examples 1 and ₂ . That is, a mixed gas having a relative humidity of 0% or 100% (CO ₂ gas 5%, N ₂ gas 95%) by a membrane temperature of 40 ° C., a bubbler temperature of 40 ° C., and a differential pressure method (atmospheric pressure on the supply side, reduced pressure on the transmission side) Is supplied to the gas separation membrane, and the permeation speeds Q _CO2 and Q _N2 (m ³ (STP) m ⁻² s ⁻¹ Pa ⁻¹ ) of the gas that has passed through the separation membrane are measured using a gas chromatography and a flow meter , Q _CO2 / Q _N2 selectivity (P _CO2 / P _N2 ) was calculated. The results are shown in Table 2.

As is apparent from the above table, the carbon films (Examples 1 to 11) carrying the alkali metal, alkaline earth metal and / or amine compound are compared with the carbon films (Comparative Examples 1 to 2) which are not carried. Remarkably excellent Q _CO2 / Q _N2 selectivity was exhibited. In addition, the carbon films (Examples 1 to 11) supporting the alkali metal, alkaline earth metal and / or amine compound contain moisture when the mixed gas contains moisture (relative humidity 100%). The Q _CO2 / Q _N2 selectivity was superior to the case where it was not included (relative humidity 0%).

The gas separation membrane of the present invention is used for applications for separating CO ₂ and other gases (for example, N ₂ ). For example, CO from combustion exhaust gas generated in a thermal power plant, a steel plant, etc. Useful in _two separations.

Claims (13)

  A gas separation membrane comprising an alkali metal, an alkaline earth metal and / or an amine compound supported on a carbon membrane made from a carded polyimide.   The gas separation membrane according to claim 1, wherein an alkali metal, an alkaline earth metal and / or an amine compound is supported on the surface and / or inside of the carbon membrane.   The gas separation membrane according to claim 1 or 2, wherein the carbon membrane is laminated on one surface of a porous support membrane.   The gas separation membrane according to claim 3, wherein the porous support membrane is tubular.   The gas separation membrane according to claim 3 or 4, wherein the porous support membrane is an alumina porous membrane.   The gas separation membrane according to any one of claims 1 to 5, wherein the carbon membrane is an asymmetric membrane.   The gas separation membrane according to any one of claims 1 to 6, wherein the alkali metal is lithium, sodium, potassium, rubidium or cesium, and the alkaline earth metal is calcium, strontium or barium.   The gas separation membrane according to any one of claims 1 to 7, wherein the amine compound is an aliphatic amine compound, an aromatic amine compound, or an amino acid. Film temperature 40 ° C., bubbler temperature 40 ° C., differential pressure in feed gas composition _{CO 2 / N 2 (5 /} 95vol%) ( supply side atmospheric pressure, permeate side vacuum) separation factor alpha _{(P CO2} obtained by measuring at / P _N2 ) is the formula 1

The gas separation membrane according to any one of claims 1 to 8, wherein CO ₂ permeance (Q _CO2 ) obtained by measurement with a differential pressure method (supply-side atmospheric pressure, permeation-side reduced pressure) with a membrane temperature of 40 ° C., a bubbler temperature of 40 ° C., and a supply gas composition CO ₂ / N ₂ (5/95 vol%). ) Is the formula 2

The gas separation membrane according to any one of claims 1 to 9, which has a relationship of   After forming a coating layer on the outer surface of the porous support membrane by dip coating with a cardo type polyimide solution, the coating layer is carbonized by heating in an anaerobic atmosphere, and then an alkali metal salt is formed. Gas separation comprising: dipping in a solution containing an alkaline earth metal salt and / or an amine compound and then drying and supporting the alkali metal, alkaline earth metal and / or amine compound on the carbon membrane A method for producing a membrane.   A coating layer is formed on the outer surface of the porous support membrane by dip coating of a solution containing a cardotype polyimide and an alkali metal salt and / or an alkaline earth metal salt, and then heated in an anaerobic atmosphere. A method for producing a gas separation membrane comprising carbonizing a coating layer to form a carbon membrane and simultaneously supporting the alkali metal and / or alkaline earth metal on the carbon membrane. Using a gas separation membrane according to any one of claims 1 to 10, a method for separating CO ₂ from a gas mixture containing CO _2.